Rudder arrangement



Aug. 16, 1932. F. HITZLER RUDDER ARRANGEMENT Filed Oct. 7, 1930' 2Sheets-Sheet l INVENTOR FRANZ H1 721.2

A TTQR/YEXS Aug. 16, 1932. F. HITZLER 1,872,038

RUDDER ARRANGEMENT Filed Oct. 7, 1 30 2 Sheets-Sheet 2 mam/r0? 7722275 5223162" 5y g/MMCQ Patented Aug. 16, 1932 UNITED RUDDER ARRANGEMENTApplication filed October 7, 1930, Serial No. 487,007, and in GermanyAugust 2, 1930.

The subject of the present invention is a rudder arrangement in whichthree or more rudders rotatably mounted in the body of the ship areused, the shafts of these rudders 6 being connected together by rods orgearings.

It is novel to arrange the rudder surfaces in such a manner that, forexample, in the case of single screw ships with three rudders twothereof are arranged at the same distance 9 behind the screws onopposite sides of the screw shaft and within the range of the screwstream, whilst the third rudder is arranged along the axis of the screwlateral rudders in such a manner that inflow conditions and rudderaction of this middle rudder are considerably improved relatively toknown rudder arrangements.

Fig. 1 is a general diagram of the invention applied to a single screwvessel,

Fig. 2 is a similar diagram of the invention applied to a twin screwvessel,

Fig. 3 is a diagram illustrating the flow of fluid around the rudders ofthe invention,

Fig. 4 is a. view of the rudder shafts con- 25 nection,

Fig. 5 shows the use of modified rudders with the invention and, I

Fig. 6 is a. diagram illustrating stream flow as modified by theinvention.

An example of construction of the invention is illustrated in Figure 1.In the horizontal section along the screw axis, a indicates the screw, 6the two lateral rudders, c the middle rudder, (Z the shafts of thelateral rudders and e the shaft of the middle rudder. The flowconditions when moving the rudders are indicated by stream lines and itwill be seen that the part of the propeller stream included by thelateral rudders re ceives a restriction, whereas when setting therudders it flows between the lateral rudders and is diverted. Therestriction of the cross section of flow between the rudders relativelyto that at the inlet edge thereof corresponds in the example ofconstruction to the distances 8 and 26 indicated in the drawing andapparently increases with the rudder angle.

Consequently the inflow speed for the middle rudder in the arrangementof the lateral behind the two res PATENT OFFICE W rudders according tothe inventionis considerably higher than without these as is'also therudder action which asis well known considerably increases with theinflow veloc ity. A further favourable action resides therein that thepropeller stream, before reaching the middle rudder, 'is whirled by thelateral rudders acting as guide'surfaces and its whirling movement isreduced, further' therein that the inflow angle for the suction side ofthe middle rudder, mainly with larger rudder angles, is reduced wherebyflowing ofl" phenomena on the suction side. of the rudder are prevented.The latter ac tion, however, only occurs when the distance of the middlerudder from the lateral rudders is such that the shaft of the middlerudder is within the angle formed by the extensions of-the sideruddersurfaces in their hard rudder posit-ions'so that the water flowingfrom the'pressure side of the lateral rudder located on the outside ofthe circle of rotation flows against the suction side of the middlerudder. j V 1 i Rudder arrangements are known in which as in accordancewith the present invention the inflow conditions and rudder actions areimproved as regards the rudders located at the back by stepping therudder surfaces in the inflow direction. In such cases, however, i

the middle rudder located behind the screw serves to direct the screwstream at the beginning of the movement of therudder towards the lateralrudder located on the inner side of the circle of rotation so that forthese rudders the inflow velocity is increased relatively to the deadwater velocity, as without the action of the middle rudder it wouldliewholly or for the larger part in" dead water, whilst the outer lateralrudders when steering remains in any case in dead water, that is to saydoes not partake of the favourable action of the middle rudder.

In contrast with this a feature of the present invention resides in thefact that all rud- 9 ders during the steering operation lie in the screwstream and a further feature residesin the fact that when operating therudders the inflow velocity for the middle rudder is increased so thatthe inflow velocity for the two lateral rudders correspondssubstantially with the velocity of the stream leaving the screw and forthe middle rudder to an increased velocity produced by the restrictionof the stream by flowing between the lateral rudders.

In Figure 2 is illustrated a further example of construction of theinvention for twin screw ships. The two lateral rudders which are againindicated by b, are located within the range of the screw streams of thescrews 9 and h, the middle rudder 0 in the middle plane of the ship. Therudders in this case are constructed as rudders having a water cuttingshape. From the stream linesindicated it will be seen that in thisexample of construction for twin screw ships fundamentally the sameactions are obtained as in the example of construction for single screwships according to Figure 1.

In Figure 3 is illustrated an example cf construction in which therudders during the setting of the rudders acquire differently largerudder angles and in this example of construction the middle rudder 0moves in advance of the lateral rudders b so that by reason of thegradual reduction ofthe passage 7 area between the middle rudder and theinner lateral rudders the inflow velocities of rudder actions arefurther increased within the range of the two rudders. 1 I

The arrangement according to the invention can also be used for triplescrew ships in which case the side rudders are arranged within the rangeof the outer screws and the middle rudder along the axis of the middlescrew. V i Fig. 4 shows the connection of the rudder shafts. The shaftsd and e are rigidly connected with levers i interconnected by bars 76.Therudders always move in the samedirection and are rotated through thesame angle due to the equal leng'th of the connecting members. Therotary moment necessary for steering is transmitted by a" rudderquadrant to one of the rudder shafts and simultane ously to the othershafts. I

Instead of balance rudders it is also possible to use for the lateralrudders rudders of a different construction for example rudders with afixed leading head shown in Fig. 5 without modifying the nature of theinven tion. The arrangement according to the invention is alsoapplicable in all cases where air or water streams are to be usedfor'depth or lateral steering.

A rudder lying in the direction of the flow is arranged in front of asecond rudder in such a way that in operation the back edge of theforward rudder situated at the exterior edge of the back rudder untilthere is only little space left in between, this movement taking placein such a way that when the angle between the rudders increases, theflow-in velocity increases for the backrudder and that a tearing 0d ofthe flow at the back side of the rudder is eliminated because the flowis directed to that side. From practical experience it is known, thatthe flow is torn off in the case of bent rudders as well as straightrudders, just behind the forward edge of the back of the rudder,approximately at the point p of Fig. 6, the stream being here separatedfrom the rudder body and being changed into a turbulence. The change ofdirection of the stream around the forward edge of the rudder takesplace by means of the steam or directed by the forward rudder, inaccordance with this invention. So to say, the angle of flow isdiminished by the forward rudder for the back side of theback rudder,the velocity is, however, increased simultaneously so thatthe rudderpressure can be considerably increased beyond the critical angle offlow.

I claim 1. In the device of the character described, two forward ruddersarranged in the same cross-ship plane, a third back rudder arran ed inthe middle and behind said two forward rudders, a shaft for each of saidrudders rotatably mounted in the ship body,

means connect-in said rudder shafts with each other, and a drivingdevice rotating said rudder shafts simultaneously in the same direction,the bacl: edge of the one of said two forward rudders which lies at theexterior side of the circle of rotation of the ship approaching inoperation the forward edge of said third back rudder so that the flowvelocity for said third rudder increases with the increase of the rudderangle and a'tearing off of the flow is avoided.

2. The device in accordance with claim 1 wherein the first-mentioned tworudders are arranged behind the screw symmetrically to the middleplaneof the ship, said third-mentioned rudder being arranged. within saidplane, the guiding surfaces of the two firstmentione'd ruddersdiminishing the losses due to the rotation of the screw stream andincreasing the-energy thereof during its flow to the third-mentionedrudder.

3. The device in accordance with'claim 1, wherein said m ans forconnecting said rudder shafts with each other in operation producediflerent rudder angles for said rudders.

In testin'iony,whereof- I have allixed my signature.

FRAN Z HITZLER.

